High-power ultracapacitor energy storage pack and method of use

ABSTRACT

An ultracapacitor energy storage cell pack includes an ultracapacitor assembly including a plurality of parallel ultracapacitors and balancing resistors in series; an enclosure for the ultracapacitor assembly; a controller; one or more temperature sensors; a pack voltage sensor; a GFI sensor; one or more cooling fans carried by the enclosure; an on/off relay coupled to the ultracapacitor assembly and the controller, the on/off relay activated by the controller during normal operation of the ultracapacitor assembly and deactivated by the controller when the GFI sensor detects a ground fault interrupt condition, the one or more temperature sensors detect an over-temperature condition, or the pack voltage sensor detects an over-voltage condition; and a pre-charge resistor and a pre-charge relay coupled to the ultracapacitor assembly and the controller, and activated by the controller to cause the pre-charge resistor to limit pack charge current until the ultracapacitor assembly reaches a minimum voltage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 10/720,916, filed Nov. 24, 2003, issued as U.S. Pat. No.7,085,112 on Aug. 1, 2006, which is a continuation-in-part applicationof U.S. patent application Ser. No. 09/972,085, filed Oct. 4, 2001,issued as U.S. Pat. No. 6,714,391 on Mar. 30, 2004. Theseapplications/patents are incorporated by reference herein as though setforth in full.

FIELD OF THE INVENTION

The field of the invention relates to a high-voltage, high-powerultracapacitor energy storage pack composed of a large number ofserially connected individual low-voltage ultracapacitor cells thatstore an electrical charge.

BACKGROUND OF THE INVENTION

The connecting together of individual battery cells for high-voltage,high-energy applications is well known. However, the chemical reactionthat occurs internal to a battery during charging and dischargingtypically limits deep-cycle battery life to hundreds of charge/dischargecycles. This characteristic means that the battery pack has to bereplaced at a high cost one or more times during the life of ahybrid-electric or all-electric vehicle. Batteries are somewhatpower-limited because the chemical reaction therein limits the rate atwhich batteries can accept energy during charging and supply energyduring discharging. In a hybrid-electric vehicle application, batterypower limitations restrict the drive system efficiency in capturingbraking energy through regeneration and supplying power foracceleration.

Ultracapacitors are attractive because they can be connected together,similar to batteries, for high-voltage applications; have an extendedlife of hundreds of thousands of charge/discharge cycles; and can acceptand supply much higher power than similar battery packs. Althoughultracapacitors are typically more expensive than battery packs for thesame applications and cannot store as much energy as battery packs,ultracapacitor packs are projected to last the life of the vehicle andoffer better fuel-efficient operation through braking regenerationenergy capture and supplying of vehicle acceleration power.

During charging and discharging operation of the ultracapacitors,parasitic effects cause the cell temperature to increase. Cooling isrequired to minimize increased temperature operation that would degradethe energy storage and useful life of each ultracapacitor.

Low-voltage energy cells, batteries, or ultracapacitors are connected inseries to obtain high-voltage energy storage. Because of variations inmaterials and manufacturing, energy storage cells are not perfectlymatched. As the serially connected pack operates through multiple chargeand discharge cycles, the cell differences cause the energy storage tobecome more and more imbalanced among the cells. The energy storageimbalance from cell to cell limits the performance of the overall packand can shorten the life of the individual cells.

Packs of batteries and packs of ultracapacitors have been built invarious forms and configurations. Various different wiring harnesses,buss bars, and connections have been used for current routing andvoltage monitoring. Various different types of circuits for charging,discharging, and equalizing have also been built. Energy storage cellshave been mounted in various “egg crate” or “wine rack” style verticaland horizontal support structures. High-voltage packages containbatteries enclosed within a single pack. Batteries have even beenconnected together by simply touching under some pressure the positiveend of one battery against the negative end of another battery such ascan be found in flashlights, small toys and appliances. High-energypacks usually include some form of convection air or liquid cooling.

SUMMARY OF THE INVENTION

The present invention involves an ultracapacitor high-energy storagepack with structural support, environmental protection, automaticcooling, electrical interconnection of the ultracapacitors, remoteON/OFF switching, a safety pre-charge circuit, a safety and automaticequalizing discharge circuit, a programmable logic controller, a digitalinterface to a control area data network for control and statusreporting, and an optional fire sensing and suppression system. The packis ideal for high-voltage, high-power applications of electric andhybrid-electric vehicle propulsion systems, fixed site high-power loadaveraging, and high-power impulse requirements. The pack is housed in analuminum box enclosure with a detachable access lid. The inside of thebox has a thick anti corrosion, electrically insulating coating. The boxhas holes cut out for the mounting of cooling fans, air intakes, andelectrical connections. The air intake cutouts have provision formounting external replaceable air filters that can be serviced withoutopening the box. Mounted to the interior of the box are aluminum guidesupport strips for three plastic support plates. Plastic, as anon-conductive material, provides for the safe operation of thehigh-voltage connections. Two of the plastic plates have wine rack holecutouts that form the support structure for individual cylindricalultracapacitor cans and the third plastic plate has pre mounted bussbars and smaller holes for fastening bolts. The first two plastic platesstructurally support and separate the ultracapacitors to provide spacefor cooling airflow along the direction of the plates. The third platesupports and positions the cans by the threaded end terminals that arebolted to the plate. Buss bars are fastened to the inside of the thirdplate to provide connections between adjacent rows of ultracapacitors.The cans, which are arranged in rows of three, are electrically andstructurally connected together with threaded studs and buss bars.

In a preferred embodiment, the triple can connections are arranged fourrows deep and twelve rows along the top to efficiently packageone-hundred and forty four (144) cylindrically shaped ultracapacitorcans with threaded polarized connections at each end of the can. Fordifferent design requirements, the longitudinal dimension of the box maybe shortened or lengthened to respectively delete or add one or morelayers of twelve (12) ultracapacitors. Similarly, the depth dimension ofthe box may be shortened or lengthened to respectively delete or add alayer of thirty-six (36) ultracapacitors. Again similarly, the widthdimension of the box may be shortened or lengthened to respectivelydelete or add a layer of forty-eight (48) ultracapacitors.

In addition to the ultracapacitors, the box houses and has mountingprovision for other electrical components. Temperature sensors andcontrollers switch the forced-air cooling fans on and off for thermalmanagement of the ultracapacitor environment. A pre-charge resistor isautomatically switched in series with the power charge circuit whenfirst turned on to prevent overloading the charging energy source.High-power relays called contactors provide remote controlled switchingof the energy storage pack into and out of the charge and load circuits.An integral Control Area Network (CAN) controller is connected tomultiple pin electronics connectors to report status parameters andcontrol the switching of the energy storage pack through a CAN digitaldata network. The pack also contains integral Ground Fault Interrupter(GFI) and fire sensing automatic safety shutoff systems.

Finally, a balancing or drain resistor is mounted in parallel aroundeach ultracapacitor to safely discharge the pack to an inactive stateover a period of time. This periodic discharge function also serves toequalize all the ultracapacitors energy storage to a balanced condition.

A further aspect of the invention involves an ultracapacitor energystorage cell pack including an ultracapacitor assembly having aplurality of parallel ultracapacitors and balancing resistors in series,each balancing resistor in parallel with each ultracapacitor toautomatically discharge each ultracapacitor over time, thereby balancingthe ultracapacitors of the ultracapacitor assembly; an enclosure toenclose and protect the ultracapacitor assembly; a controller for theultracapacitor assembly; one or more temperature sensors to monitortemperature of the ultracapacitor assembly and coupled to thecontroller; a pack voltage sensor to monitor voltage of theultracapacitor assembly and coupled to the controller; a GFI sensor tomonitor for a ground fault interrupt condition of the ultracapacitorassembly and coupled to the controller; one or more cooling fans carriedby the enclosure and controlled by the controller to cool theultracapacitor assembly based upon temperature sensed by the one or moretemperature sensors; an on/off relay coupled to the ultracapacitorassembly and the controller, the on/off relay activated by thecontroller during normal operation of the ultracapacitor assembly anddeactivated by the controller when the GFI sensor detects a ground faultinterrupt condition, when the one or more temperature sensors detect anover-temperature condition, or when the pack voltage sensor detects anover-voltage condition; and a pre-charge resistor and a pre-charge relaycoupled to the ultracapacitor assembly and the controller, thepre-charge relay activated by the controller to cause the pre-chargeresistor to limit pack charge current until the ultracapacitor assemblyreaches a minimum voltage.

Another aspect of the invention involves a method of using anultracapacitor energy storage cell pack including the steps of providingan ultracapacitor energy storage cell pack including a ultracapacitorassembly having a plurality of parallel ultracapacitors and balancingresistor in series, each balancing resistor in parallel with eachultracapacitor to automatically discharge each ultracapacitor over time,thereby balancing the ultracapacitors of the ultracapacitor assembly andassuring a safe condition for service personnel; an enclosure to encloseand protect the ultracapacitor assembly; a controller for theultracapacitor assembly; one or more temperature sensors to monitortemperature of the ultracapacitor assembly and coupled to thecontroller; a pack voltage sensor to monitor voltage of theultracapacitor assembly and coupled to the controller; a GFI sensor tomonitor for a ground fault interrupt condition of the ultracapacitorassembly and coupled to the controller; one or more cooling fans carriedby the enclosure and controlled by the controller to cool theultracapacitor assembly based upon temperature sensed by the one or moretemperature sensors; an on/off relay coupled to the ultracapacitorassembly and the controller, the on/off relay activated by thecontroller during normal operation of the ultracapacitor assembly anddeactivated by the controller when the GFI sensor detects a ground faultinterrupt condition, when the one or more temperature sensors detect anover-temperature condition, or when the pack voltage sensor detects anover-voltage condition; and a pre-charge resistor and a pre-charge relaycoupled to the ultracapacitor assembly and the controller, thepre-charge relay activated by the controller to cause the pre-chargeresistor to limit pack charge current until the ultracapacitor assemblyreaches a minimum voltage; automatically discharging the ultracapacitorsof the ultracapacitor energy storage cell with the balancing resistorsto balance ultracapacitors of the ultracapacitor assembly and assure asafe condition for service personnel; cooling the ultracapacitorassembly with the one or more cooling fans based upon temperature sensedby the one or more temperature sensors; activating the on/off relay withthe controller during normal operation of the ultracapacitor assemblyand deactivating the on/off relay with the controller when the GFIsensor detects a ground fault interrupt condition, when the one or moretemperature sensors detect an over-temperature condition, or when thepack voltage sensor detects an over-voltage condition; and activatingthe pre-charge relay with the controller to cause the pre-chargeresistor to limit pack charge current until the ultracapacitor assemblyreaches a minimum voltage.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthis specification, illustrate embodiments of the invention and togetherwith the description, serve to explain the principles of this invention.

FIG. 1 is an exploded perspective view drawing of an embodiment of ahalf module of an ultracapacitor energy storage cell pack.

FIG. 2 is a perspective view of an embodiment of an ultracapacitorenergy storage cell pack.

FIG. 3 is a top plan view of an embodiment of a circuit board for thehalf module illustrated in FIG. 1 and ultracapacitor energy storage cellpack illustrated in FIG. 2.

FIG. 4 is an exploded perspective view of an alternative embodiment of aultracapacitor energy storage cell pack.

FIG. 5 is an exploded perspective view of the ultracapacitors andsupport plates of the ultracapacitor energy storage cell pack of FIG. 4.

FIG. 6 is perspective detail view taken of detail 6 of theultracapacitors, threaded interconnections between the ultracapacitors,and parallel drain resistors mounted with ring terminals of theultracapacitor energy storage cell pack of FIG. 5.

FIG. 7 is a side-elevational view of an embodiment of a middle supportplate of the ultracapacitor energy storage cell pack illustrated in FIG.4, and the middle support plate is shown with cutouts for theultracapacitors and the drain resistors.

FIG. 8 is a side-elevational view of an embodiment of an end supportplate of the ultracapacitor energy storage cell pack illustrated in FIG.4, and the end support plate is shown with cutouts for the mountingbolts and the support guide mounting rivets.

FIG. 9 is a block diagram of the ultracapacitor energy storage cell packillustrated in FIG. 4.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to FIGS. 1 and 2, an embodiment of an ultracapacitorenergy storage cell pack 10 will now be described. FIG. 1 illustrates anexploded view of an embodiment of a half module 15 of the ultracapacitorenergy storage cell pack 10. FIG. 2 illustrates an embodiment of anassembled ultracapacitor energy storage cell pack module 10, whichincludes two half modules 15 fastened together. Although each halfmodule 15 preferably includes eighty ultracapacitors 20, each halfmodule may have other numbers of ultracapacitors 20. Further, theultracapacitor pack 10 may have other numbers of modules 15 besides apair (e.g., 1, 3, 4, etc.).

The ultracapacitor pack 10 is shown in exploded view in FIG. 1 toillustrate the different levels in the half module 15 that are addedduring assembly of the half module 15. Each of these levels will now bedescribed in turn below followed by a description of the assemblyprocess.

An aluminum base plate 25 forms a bottom or inner-most level of the halfmodule 15. The base plate 25 includes a welded frame 30 around edges ofthe base plate 25.

A polycarbonate crate plate 35 is seated inside the frame 30 andincludes cutouts or holes 40 with a shape that matches the cross-sectionof the ultracapacitors 20. The base plate 25 and crate cutouts 40 forman x, y, and z location and mounting support for the ultracapacitors 20.The cutouts 40 also prevent the ultracapacitors 20 from rotating duringuse, e.g., mobile vehicle use.

In the embodiment shown, the individual ultracapacitors 20 have ageneral square-can shape (i.e., rectangular parallelpiped). Thecross-section of the ultracapacitors 20 is 2.38 in. by 2.38 in. and thelength is about 6 in. On an upper-most or outer-most end of theultracapacitor 20, two threaded lug terminals 45 and a dielectric pastefill port 50 protrude from an insulated cover 55 of the ultracapacitor20. The cover 55 of the ultracapacitor may include a well encircled by aprotruding rim. Shrink plastic that normally surrounds sides or exteriorcapacitor casing 60 of the ultracapacitor 20 is removed to better exposethe exterior casing 60 to circulated cooling air. The shrink plastic maybe left on the bottom of the ultracapacitor 20.

A box frame 65 ties together the base plate 25 and frame 30 with circuitboards 70, and a top polycarbonate cover 75. The box frame 65 haselongated lateral cutouts 80 on two opposing sides to provide forcross-flow air cooling. Bottom flanges 85 provide a mounting surface totie two of these box frames 65, and, hence, two half modules 15,together to form the single ultracapacitor pack module 10 shown in FIG.2. The box frame 65 includes a large upper rectangular opening and alarge lower rectangular opening.

The next layer is a first ¼-in. foam rubber insulating and sealing sheet90 that covers the ultracapacitors 20. The first sheet 90 has cutoutsfor the ultracapacitor terminals 45 and fill port 50 so that the sheet90 can seal tightly against the cover 55 of the ultracapacitor 20.

A second ⅛-in. foam rubber insulating and sealing sheet 95 may be placedon top of the previous first sheet 90. The second sheet 95 includesrectangular cutouts or holes 100. The cutouts 100 receive copper barelectrical interconnections 105. The cutouts 100 in the sheet 95simplify the assembly and proper placement of the copper bar electricalinterconnections 105. The sheet 95 also seals the copper bar electricalinterconnections 105. The copper bar electrical interconnections 105include holes that the ultracapacitor terminals 45 protrude through.

Two identical main circuit boards 70 (e.g., 40-ultracapacitor maincircuit boards) may lay on top of the foam rubber sheets 90, 95. Withreference additionally to FIG. 3, each main circuit board 70 may includeholes 107 that the ultracapacitor terminals 45 protrude through. In theembodiment shown, each circuit board 70 may have mounting holes 107 for40 (8 by 5) ultracapacitors less two corner positions required for framestructure mounting. Instead of two circuit boards 70, a single circuitboard 70 may be used. Thus, as used herein, the word “circuit board”means one or more circuit boards. Fasteners such as lug nuts fasten theindividual ultracapacitor terminals 45 and copper bars 105 to thecircuit boards 70 and compress the foam rubber sheets 90, 95 in betweenthe cover 55 of the ultracapacitor 20 and the circuit boards 70. Thus,the circuit board 70 forms the location and mechanical support as wellas the electrical connections for the ultracapacitors 20. The foamsheets 90, 95 seal around the rim of the ultracapacitor terminals 45. Aprocessor and display circuit board mounts on top of the main circuitboard 70.

Although the ultracapacitor pack 10 and the half modules 15 are shown asbeing generally rectangular in shape, either or both may have shapesother than generally rectangular such as, but not by way of limitation,circular, oval, other curvilinear shapes, other rectilinear shapes, andother polygonal shapes.

A top aluminum frame 110 and the transparent polycarbonate cover 75 mayattach to the frame structure to complete the half module 15. Thetransparent cover 75 allows observation of a light emitting diode (LED)failure detection display that indicates the active/inactive status ofthe ultracapacitors 20.

Together, the bottom base plate 25, crate plate 35, box frame 65,sealing sheets 90, 95, and circuit board(s) 70, and ultracapacitorterminal fasteners form an ultracapacitor mounting assembly 112 for theultracapacitors 20. The ultracapacitor mounting assembly 112 provides amounting surface for the copper bar interconnects 105, maintains theposition and spacing of the ultracapacitors 20 in the X, Y, and Zdirections, does not allow the ultracapacitors to rotate when connected,and the main circuit board(s) 70 provides a mounting platform for thecell equalization, failure detection, processor, and LED displaysystems. Attaching the ultracapacitors 20 to the mounting assembly 112by the terminals 45 instead of the exterior ultracapacitor casing 60allows the ultracapacitors 20 to be more effectively cooled because themajority of the surface area of the ultracapacitors 20 is in the coolingair stream supplied by the cross-flow air cooling assembly 115. Sealingalong the cover 55 and around the terminals 45 protects the terminals 45from water, dust, and other contaminants.

An exemplary method of assembling the ultracapacitor half module 15 willnow be described. The ultracapacitors 20 are first placed onto thebottom base plate 25, with the bottoms of the ultracapacitors 20extending through the square cutouts 40 of the crate plate 35. The boxframe 65 is applied over the ultracapacitors 20, so that theultracapacitors extend through the large lower and upper rectangularopenings of the box frame 65. The ¼-in. foam rubber insulating andsealing sheet 90 is placed on top of the ultracapacitors 20, with theultracapacitor terminals 45 and fill port 50 protruding through cutoutsin the sheet 90. The ⅛-in. foam rubber insulating and sealing sheet 95is placed on top of the previous sheet 90 and the copper bar electricalinterconnections 105 are placed into the rectangular cutouts 100 of thesheet 95. The ultracapacitor terminals 45 also protrude through holes inthe copper bar electrical interconnections 105. The main circuit boards70 are layered on top of the foam rubber sheets 90, 95 so that thethreaded ultracapacitor terminals 45 protrude through the correspondingholes in the circuit boards 70. Lug nuts are screwed onto the threadedterminals 45, compressing the foam rubber sheets 90, 95 in between thecover 55 of the ultracapacitor 20 and the circuit boards 70, andsecuring the ultracapacitors 20 and copper bars 105 in position. Theprocessor and display circuit board is mounted on top of the maincircuit board 70. The top aluminum frame 110 and the transparentpolycarbonate cover 75 are placed over the circuit boards and attachedto the frame structure to complete the half module 15. A pair of halfmodules 15 may be positioned back to back (i.e., facing oppositedirections with the bottoms of the aluminum base plates 25 touching) anda cross-flow air cooling assembly 115 may be attached to the framestructure, adjacent the elongated lateral cutouts 80 on one side of thebox frames 65. The half modules 15 may be bolted or otherwise fastenedtogether at the respective bottom flanges 85 to complete theultracapacitor pack module 10.

To determine if one or more ultracapacitors 20 in the pack 10 need to bereplaced, a user observes the light emitting diode (LED) failuredetection display through the transparent cover 75. The LED failuredetection display includes an array of LEDs that correspond to the arrayof ultracapacitors 20, each LED indicating the status of a correspondingultracapacitor 20. Each unlit LED indicates a corresponding failed LED.An ultracapacitor 20 in the pack 10 can quickly and easily be replacedby simply unfastening the frame and unbolting only the failedultracapacitor 20 that had been previously identified by the LEDdisplay. The replacement ultracapacitor is put into position and theprocedure reversed.

With reference to FIGS. 4-9, and initially, FIGS. 4 and 5, anultracapacitor energy storage cell pack (hereinafter “ultracapacitorpack) 200 constructed in accordance with another embodiment of theinvention will now be described. The ultracapacitor pack 200 includes aultracapacitor cell and winerack support assembly (hereinafter“ultracapacitor assembly”) 210, an ultracapacitor pack box enclosure(hereinafter “box enclosure”) 220, a metal lid 230, an air filterbracket 240 (w/air filter), cooling fans 250, fan finger guards 260,higher-power precharge resistor 270, Programmable Logic Controllermodule (hereinafter “PLC”) 280, high power relays (kilovac contactors)290, electrical connectors 300, 310, 320 and other discrete componentsmounted within the box enclosure 220.

The ultracapacitor assembly 210 includes one-hundred and forty-four(144) ultracapacitors 330 connected in series to provide a nominal 360volts DC, 325 watt-hours energy storage. The value of eachultracapacitor 330 is 2600 Farads. In alternative embodiments, theultracapacitor assembly 210 may have other numbers of ultracapacitors,different types of ultracapacitors, and/or an overall different amountof voltage and/or power. Each ultracapacitor 330 is connected with aparallel drain resistor 340 (FIG. 6). The ultracapacitor assembly 210includes a first wine rack middle support plate 350, a similar secondwine rack middle support plate 360, and a wine rack end support plate370 for supporting the ultracapacitors 330.

The box enclosure 220 is preferably made of metal and includes squareend cutouts 380 in rear wall 382 to accommodate air flow therethroughand circular cutouts 390 in front wall 392 to accommodate the coolingfans 250. The front wall 392 and rear wall 382 are joined by oppositeparallel side walls 394. The filter(s) of the air filter bracket 240 isexternally serviceable and fits over the square cutouts 380 of the rearwall 382. The interior of the box enclosure 220 and underside of the lid230 is coated with a thick material that provides electrical insulationand corrosion protection as an additional level of safety for the boxenclosure 220. The inner bottom of the box enclosure 220 includessupport plate guides for mounting the wine rack middle support plates350, 360 and end support plate 370.

FIG. 5 shows an exploded view of the ultracapacitor assembly 210. Theultracapacitors 330 are cylindrical canisters with aluminum femalethreaded connections at each end, which receive male threaded aluminuminterconnection studs 400 for connecting the ultracapacitors 330 inseries. Aluminum bus bars 410 and aluminum interconnection washers arealso used to interconnect the ultracapacitors 330 in series at the endsof the rows. Providing electrical connections made of aluminum metalprevents any corrosive galvanic effects from dissimilar metals.Additionally, the threaded connections are covered with a silicondielectric grease to prohibit environmentally caused corrosion.

The wine rack middle support plates 350, 360 and end support plate 370are made of nonconductive plastic material to prevent any high-voltagearcing or other high-voltage leakage effects that could occur over timedue to vibration and shock. The wine rack middle support plates 350, 360and end support plate 370 are different in construction to allow ease ofassembly and replacement of any canister row.

With reference to FIG. 7, the wine rack middle support plates 350, 360include a pattern of generally circular cutouts 430 for receiving theultracapacitors 330. The cutouts 430 include an additional semi-circularrecess 440 to accommodate and support the drain resistors 340. The drainresistors 340 are preformed with ring terminals 442 (FIG. 6) attached toleads of the drain resistors 340 for simplicity of mounting andelectrical connection. Additional semi-circular recesses 450 along a topedge 460 and bottom edge 470 of the wine rack middle support plates 350,360 provide clearance for the attaching rivets of support guides on abottom of box enclosure 220 and the lid 230. The wine rack middlesupport plates 350, 360 are made of 3/16″ thick polycarbonate plasticfor strength and electrical insulation.

With reference to FIG. 8, the wine rack end support plate 370 includes apattern of circular holes 480 for receiving threaded bolt fasteners formounting the ultracapacitors 330. Additional semi-circular recesses 490along a top edge 500 and a bottom edge 510 of the wine rack end supportplate 370 provide clearance for the attaching rivets of support guideson a bottom of the box enclosure 220 and the lid 230. The wine rack endsupport plate 370 is made of 3/16″ thick Grade G-10/FR4 Garolite glassfabric laminate with an epoxy resin that absorbs virtually no water andholds its shape well. Inside-mounted aluminum bus bars 410 are affixedin place to the wine rack end support plate 370 with silicon RTV (RoomTemperature Vulcanizing, which is a common jelly-like paste that curesto a rubbery substance used in various applications as adhesive and/orsealer). The bus bars 410 are pre-positioned to avoid confusion thatcould cause assembly mistakes.

FIG. 9 is a general block diagram of the ultracapacitor pack 200. Asindicated above, each ultracapacitor 330 is connected in parallel withthe drain resistor 340. One-hundred and forty-four (144) of theseparallel connections are connected in series to provide a nominal 360volts DC, 325 watt-hours energy storage. The value of eachultracapacitor 330 is 2600 Farads and the value and power of the drainresistor 340 is selected to completely discharge the ultracapacitor 330over a number of hours during an inactive period of the ultracapacitorpack 200. The energy drain action is slow enough so as not to interferewith the normal operation of the ultracapacitor pack 200. The dischargeis also slow enough so as not to cause any significant temperatureincrease from the drain resistors 340 within the ultracapacitor pack200. The chemical composition of the ultracapacitor 330 allows charge tobuild up across the ultracapacitor 330 over a period of time after theultracapacitor 330 is shorted and left open. The drain resistors 340allow a safe discharge of the high voltage of the ultracapacitor pack200 to eliminate any shock danger from the ultracapacitor “memory” topersonnel servicing the ultracapacitor pack 200.

Because the ultracapacitors 330 can accept hundreds of amperes ofelectrical current during charging, a connection to an energy sourcewould appear as a short circuit to the energy source. To accommodatethis problem, a high-power pre-charge resistor 270 with its own heatsink is mounted inside the box enclosure 220 and used to limit theinitial charging current. Based on input to a pack voltage sensor 520,the PLC 280 controls a pre-charge contactor relay 540 to engage thepre-charge resistor 270 until the ultracapacitors 330 reach a minimumsafe voltage level.

The PLC 280 is the control center for additional features. Through aControl Area Network (CAN) bus interface (e.g., SAE standard J1939), thePLC 280 offers remote ON/OFF control and status reporting of: thecontrol relay positions for on/off relay 550 and precharge relay 540,pack voltage sensor 520, ground fault interrupt (GFI) sensor 560,cooling fans 250, box temperature sensor 570, over temperature sensor580, optional fire sensor 590, and optional fire suppression system 600.The PLC 280 also uses input from the box temperature sensor 570 to turnon and off the cooling fans 250. During normal operation of theultracapacitor pack, the on/off relay 550 is activated. The on/off relay550 is deactivated by the PLC 280 when the GFI sensor 560 detects aground fault interrupt condition, when the over temperature sensor 580detects an over-temperature condition, or the pack voltage sensor 520detects an over-voltage condition. The fire suppression system 600 isactivated by the PLC 280 in the event a fire condition is detected bythe fire sensor 590 to extinguish any fire in the ultracapacitor pack200. A 360 VDC+ stud feed thru 610 is an external power cable attachmentfor the positive side of the ultracapacitor pack 200. A 360 VDC− studfeed thru 620 is an external power cable attachment for the negativeside of the ultracapacitor pack 200. A 24 VDC+, 24 VDC− power connector630 provides the positive and negative dc power connections for the PLC280. A digital data interface connector 640 includes the wires thatconnect to the CAN buss network and is also the port by which the PLC280 is programmed.

The ultracapacitor pack 200 includes structural support, environmentalprotection, automatic cooling, electrical interconnection of theultracapacitors, remote ON/OFF switching, a safety pre-charge circuit, asafety and automatic equalizing discharge circuit, a programmable logiccontroller, a digital interface to a control area data network forcontrol and status reporting, and an optional fire sensing andsuppression system. The pack is ideal for high-voltage, high-powerapplications of electric and hybrid-electric vehicle propulsion systems,fixed site high-power load averaging, and high-power impulserequirements.

While embodiments and applications of this invention have been shown anddescribed, it would be apparent to those in the field that many moremodifications are possible without departing from the inventive conceptsherein. The invention, therefore, is not to be restricted except in thespirit of the appended claims.

1. An ultracapacitor energy storage cell pack, comprising: anultracapacitor assembly including a plurality of parallelultracapacitors and balancing resistors in series, each balancingresistor in parallel with each ultracapacitor to automatically dischargeeach ultracapacitor over time, thereby balancing the ultracapacitors ofthe ultracapacitor assembly; an enclosure to enclose and protect theultracapacitor assembly; one or more temperature sensors to monitortemperature of the ultracapacitor assembly; a pack voltage sensor tomonitor voltage of the ultracapacitor assembly; a ground fault sensor tomonitor for a ground fault condition of the ultracapacitor assembly; acooling system to cool the ultracapacitor assembly; an on/off relaycoupled to the ultracapacitor assembly and a control input, the on/offrelay activated during normal operation of the ultracapacitor assemblyand deactivated by the control input to terminate normal operation; anda pre-charge resistor and a pre-charge relay coupled to theultracapacitor assembly and the control input, the pre-charge relayactivated by the control input to cause the pre-charge resistor to limitpack incoming current until the ultracapacitor assembly reaches aminimum voltage.
 2. The ultracapacitor energy storage cell pack of claim1, wherein the pack includes a controller.
 3. The ultracapacitor energystorage cell pack of claim 2, wherein the controller is coupled to oneor more of a pack temperature sensor or sensors, a pack voltage sensor,a ground fault sensor, a fire sensor, a fire suppression subsystem, acooling system control input, an on/off relay control input, and aprecharge resistor control relay input.
 4. The ultracapacitor energystorage cell pack of claim 3, wherein the controller controls one ormore of the cooling system, precharge resistor control relay input, andon/off relay from one or more of the pack temperature sensor or sensorsinput, the voltage sensor input, the ground fault input, the fire sensorinput, and the fire suppression input.
 5. The ultracapacitor energystorage cell pack of claim 3, wherein the controller has a digital datainterface to a control network.
 6. The ultracapacitor energy storagecell pack of claim 3, wherein the controller monitors and reports thesensor inputs to the control network interface, and controls the coolingsystem and on/off relay in response to commands from the networkinterface.
 7. The ultracapacitor energy storage cell pack of claim 5,wherein the controller is a programmable logic controller with a digitaldata interface to an SAE standard J1939 Control Area Network (CAN). 8.The ultracapacitor energy storage cell pack of claim 1, wherein thecooling system is one or more cooling fans carried by the enclosure. 9.The ultracapacitor energy storage cell pack of claim 8, wherein an airfilter is carried by the enclosure.
 10. The ultracapacitor energystorage cell pack of claim 1, wherein the ultracapacitor energy storagecell pack stores up to a nominal 325 watt-hours of electrical energy atup to a nominal 360 volts DC.
 11. The ultracapacitor energy storage cellpack of claim 1, wherein the enclosure includes an inside surface withan anti-corrosion and electrical insulation coating thereon.
 12. Theultracapacitor energy storage cell pack of claim 1, wherein theultracapacitor assembly includes two polycarbonate middle plate supportswith cutouts that receive the ultracapacitors and balancing resistors.13. The ultracapacitor energy storage cell pack of claim 1, wherein theultracapacitor assembly includes an end support plate made of a glassfabric laminate with an epoxy resin, and has a pattern of holes formounting the ultracapacitors.
 14. The ultracapacitor energy storage cellpack of claim 1, wherein the ultracapacitors are mechanically andelectrically interconnected with aluminum connections.
 15. Theultracapacitor energy storage cell pack of claim 1, further including afire sensor and a fire suppression subsystem activated upon a fireindication input from the fire sensor.